I don't understand how someone has a problem with that happened with Bruce in TDKR, but yet they're fine when Bruce mentioned creating a symbol that's everlasting back in BB.

Maybe if TDK didn't exist, things would be different. Bruce spent that movie after a point looking for a way to shut down the Batman project, denounced copycats, wanted to leave a non-Batman successor, and retire with his childhood friend. And then he corrupted his incorruptible symbol at the end of TDK. The character as written just flip flops in whatever direction they decided to take, a very "the ends justify the means" style of writing in particular seems to be employed in TDKR.